An impact toughness test frequently used on plastics. It is related to the Charpy test, and it is frequently performed by people trained in Materials Science.

The amount of energy necessary for a pendulum to break a rectangular sample with or without a pre-formed notch in it is measured. In the event that the sample contains a pre-formed notch, it should be oriented so that the pendulum strikes the opposite side from that notch. Care must be taken to test the sample at a temperature similar to its expected operating temperature. It will exhibit a radical decrease in impact toughness below its glass transition temperature.

Some sample values include
  • Acrylic ----------- 40-130 J/m
  • Nylon 6,6 --------- 110 J/m
  • Polycarbonate ----- 850 J/m
  • Polystyrene ------- 10-110 J/m
  • Polyurethane ------ 430-1200 J/m

An IZOD test may be conducted to evaluate the fracture toughness of a new plastic, as a quality control measure in order to ensure that a batch of plastic has not been weakened unintentionally, or to determine the effectiveness of a new processing technique.

ASTM standard test D4812 is an IZOD test with an un-notched sample. ASTM standard test ASTM D256 is an IZOD test with a pre-notched sample.

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